1. Field of the Invention
The present invention relates to image pickup apparatuses.
2. Description of the Related Art
A technique is known in which, when a portion of an image pickup area is irradiated with intense light, the voltage of the output node of an amplifying unit in a pixel is clipped so that an influence is not exerted on the area surrounding the portion. For example, in Japanese Patent Laid-Open No. 2001-230974, a configuration is disclosed in which the voltage of the input node of an amplifying unit in a pixel is clipped (for example, see the sixth embodiment).
Through studies carried out by the inventors, a new issue has been found in a configuration for clipping the voltage of the input node of an amplifying unit in a pixel. Specifically, for example, it has been found that, in the case where a reset transistor in a pixel is used to clip the voltage of the input node of an amplifying unit, the degree of crosstalk of signals which occurs between pixel lines is variable depending on the voltage supplied to the gate of the reset transistor upon clipping. In the case where the reset transistor is an N-transistor, the voltage supplied to the gate of the reset transistor is set to be high, enabling the crosstalk of signals which occurs between pixel lines to be reduced. However, when the voltage supplied to the gate of the reset transistor is simply set to be high for a clipping operation, the signal saturation in a pixel may be restricted. In other words, the dynamic range of a signal of a pixel may be narrowed. That is, in the case where only one value of the voltage supplied to the gate of the reset transistor for clipping is used, only one of the following choices is to be selected: a choice of making an image pickup apparatus operate so as to suppress the crosstalk of signals which occurs between pixel lines, and a choice of making an image pickup apparatus operate so as to maintain the dynamic range of a pixel.